Articulated rail cars are well known in the railway arts and often comprise a pair of rail car platforms arranged end-to-end with the mutually adjacent ends thereof supported by a common truck bolster such as the bolster of a conventional three piece truck. In the prior art, the connection between the adjacent ends of the two car platforms, and their retention with respect to the common or center truck, has been achieved through employment of an articulated joint including complex and precisely aligned spherical bearing surfaces for achieving the rotational degrees of freedom required for such a connection. One of the two adjacent platform ends is supported on the common truck center plate surface in a conventional manner, i.e. a flat truck center plate surface supports a flat platform center plate. The other of the two adjacent platform ends is supported vertically and laterally on a spherical section that nests above the flat center plate of the first mentioned platform end. Longitudinal train action forces are transmitted between the two platforms through another set of spherical sections with the same center as the spherical sections offering vertical and horizontal support.
A wide variety of similar articulated joints or connection assemblies have been proposed in the art and purport to offer improvements in articulation, wear properties, wear take-up, and the like. Such connectors generally have provided a structure in which the connection includes a connecting pivot pin which is used to assemble the spherical segments in a manner to relate their centers of rotation to a common point for the necessary three relative rotational degrees of freedom to accommodate relative yaw, pitch and roll between the connected car bodies.
Notwithstanding their purported benefits, prior articulated connectors have exhibited certain shortcomings. For example, commercially used articulated connectors typically are costly to manufacture and difficult to assemble and disassemble. Further, critical wear can occur at the spherical bearing surfaces which transfer all the loads or forces between the ends of the interacting platforms, thus resulting in reduced vertical side bearing clearance and longitudinal slack action. Such changes result in a need for frequent side bearing clearance and slack take-up adjustment.
Vertical contacting side bearing deflections are reduced for a given car body roll angle when the relative center of longitudinal roll of the car is shorter rather than longer. For example, at one end of an articulated platform car body, a relatively flat center plate surface contact area engages the flat truck center plate. The car body thus rolls about a lateral edge of the engaged bearing surfaces, and provides a reduced radius of roll motion, with respect to the side bearings compared to the car body side bearing roll radius experienced by the opposite end of the car body which is supported on the spherical bearing section.
Prior art articulated connectors are also prone to accumulate slack and require frequent adjustment due to wear in the articulated joints in that the precision required for best performance of such prior connectors deteriorates quickly with progressive wear even if wear or slack compensation capability has been provided. That is, even where prior connectors can compensate for slack accumulation, the resultant wear nevertheless produces asymmetry with resultant binding and galling among the various cooperating spherical wear surfaces thus resulting in further accelerated rates of wear and deficiencies in connector performance.